Adsorption heat pump system and method of driving adsorption heat pump

ABSTRACT

An adsorption heat pump system includes: an adsorption heat pump including a condenser configured to condense a vapor of a refrigerant; an air-cooling device configured to air-cool a coolant discharged from the condenser in the adsorption heat pump and to resupply the air-cooled coolant to the condenser; and a controller. The controller controls a flow rate of the coolant to be supplied to the condenser according to a difference in temperature between the coolant supplied to the condenser and the coolant discharged from the condenser.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of International Patent ApplicationNo. PCT/JP2011/076864 filed Nov. 22, 2011 and designated the U.S., theentire contents of which are incorporated herein by reference.

FIELD

The embodiments discussed herein are related to an adsorption heat pumpsystem and a method of driving an adsorption heat pump.

BACKGROUND

Along with the recent advent of advanced information society, a largeamount of data has been handled by a computer, and many computers havebeen often placed and collectively managed in a single room in afacility such as a data center. In such a data center, for example, alarge number of racks (server racks) are placed in a computer room andmany computers (servers) are stored in each of the racks. Then, a largeamount of jobs are efficiently processed by organically distributing thejobs to the computers according to their respective operating statuses.

Along with the operation of the computers, a large amount of heat isgenerated from the computers. Since a high temperature inside thecomputer causes malfunction and failure, cooling of the computer isimportant. For this reason, in the data center, the room temperature isusually adjusted by using fans to discharge the heat generated from thecomputers to the outside of the racks and also using an air conditioner.

Meanwhile, in the data center, a large amount of power is consumed by anair-conditioning system. In this regard, there has been proposed atechnology to collect heat (waste heat) discharged from an electronicdevice such as a computer and to efficiently use the collected heat asenergy. In general, the temperature of the heat collected from theelectronic device such as the computer is 90° C. or less, and use of anadsorption heat pump (AHP) may make it possible to utilize the wasteheat of 90° C. or less to obtain cooling water which may be used for airconditioning, cooling of the electronic device, and the like.

-   Patent Document 1: Japanese Laid-open Patent Publication No.    08-42935

SUMMARY

According to one aspect of the disclosed technology, provided is anadsorption heat pump system including: an adsorption heat pump includinga condenser configured to condense a vapor of a refrigerant; anair-cooling device configured to air-cool a coolant discharged from thecondenser in the adsorption heat pump and to resupply the air-cooledcoolant to the condenser; and a controller configured to control a flowrate of the coolant to be supplied to the condenser according to adifference in temperature between the coolant supplied to the condenserand the coolant discharged from the condenser.

According to another aspect of the disclosed technology, provided is amethod of driving an adsorption heat pump configured to cool a coolantdischarged from a condenser in the adsorption heat pump by using anair-cooling device. The method includes: controlling a flow rate of thecoolant to be supplied to the condenser such that a difference intemperature between the coolant supplied to the condenser and thecoolant discharged from the condenser is equal to or more than a setvalue.

The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view illustrating an example of an adsorption heatpump;

FIG. 2 is a schematic view illustrating an adsorption heat pump systemaccording to a first embodiment;

FIGS. 3A and 3B are schematic views illustrating air-cooling devices ofModified Example 1;

FIG. 4 is a view (Part 1) illustrating an adsorption heat pump system ofModified Example 2;

FIG. 5 is a view (Part 2) illustrating the adsorption heat pump systemof Modified Example 2;

FIG. 6 is a view illustrating an adsorption heat pump system of ModifiedExample 3;

FIG. 7 is a view illustrating an adsorption heat pump system of anexperimental example; and

FIG. 8 is a schematic view illustrating an adsorption heat pump systemaccording to a second embodiment.

DESCRIPTION OF EMBODIMENTS

Prior to description of embodiments, a preliminary matter will be givenbelow in order to facilitate understanding of the embodiments.

FIG. 1 is a schematic view illustrating an example of an adsorption heatpump.

An adsorption heat pump 10 illustrated in FIG. 1 includes an evaporator11, a condenser 12 disposed above the evaporator 11, and adsorbers 13 aand 13 b disposed in parallel between the evaporator 11 and thecondenser 12. A space inside the adsorption heat pump 10 isdepressurized to about 1/100 atm to 1/10 atm, for example.

A cooling water pipe 11 a through which cooling water passes and a tray11 b to store a refrigerant are provided in the evaporator 11. Whilewater, alcohol or the like is used as the refrigerant, water is usedhere as the refrigerant.

In each of the adsorbers 13 a and 13 b, a heat-transfer pipe 14 and anadsorbent (desiccant) 15 are provided. The adsorber 13 a and theevaporator 11 are connected through a valve 16 a, and the adsorber 13 band the evaporator 11 are connected through a valve 16 b. As theadsorbent 15, activated carbon, silica gel, zeolite or the like is used,for example.

In the condenser 12, a cooling water pipe 12 a with a number of platefins attached thereto is disposed. A valve 17 a is disposed between thecondenser 12 and the adsorber 13 a, and a valve 17 b is disposed betweenthe condenser 12 and the adsorber 13 b.

The valves 16 a, 16 b, 17 a and 17 b are opened and closed by electricalsignals to be outputted from a controller (not illustrated), forexample. The condenser 12 and the evaporator 11 are connected by a pipe18.

Operations of the above adsorption heat pump 10 will be described below.

Here, it is assumed that the valve 16 a between the evaporator 11 andthe adsorber 13 a and the valve 17 b between the adsorber 13 b and thecondenser 12 are both open in an initial state. Meanwhile, it is assumedthat the valve 16 b between the evaporator 11 and the adsorber 13 b andthe valve 17 a between the adsorber 13 a and the condenser 12 are bothclosed. It is also assumed that cooling water is supplied to the coolingwater pipe 12 a in the condenser 12 and that hot water heated by heatdischarged from an electronic device is supplied to the heat-transferpipe 14 in the adsorber 13 b.

The pressure inside the adsorber 13 a is lowered as the adsorbent 15adsorbs moisture in the atmosphere. Since the valve 16 a between theadsorber 13 a and the evaporator 11 is open, the pressure inside theevaporator 11 is also reduced. Accordingly, the water stored in the tray11 b evaporates, depriving the cooling water pipe 11 a of latent heat.As a result, the temperature of the water passing through the coolingwater pipe 11 a is lowered, and thus low-temperature cooling water isdischarged from the cooling water pipe 11 a. This cooling water is usedfor room air conditioning, cooling of electronic devices, and the like,for example.

A water vapor generated by the evaporator 11 enters into the adsorber 13a through the valve 16 a, and is adsorbed by the adsorbent 15.

While the adsorption process is carried out in one adsorber 13 a toadsorb moisture onto the adsorbent 15, a restoration process is carriedout in the other adsorber 13 b to restore (dry) the adsorbent 15. Morespecifically, in the adsorber 13 b, the moisture adsorbed onto theadsorbent 15 is heated and turned into a water vapor by the hot waterpassing through the heat-transfer pipe 14, and then separates from theadsorbent 15. The water vapor generated in the adsorber 13 b passesthrough the open valve 17 b and then enters into the condenser 12.

The water vapor that has entered into the condenser 12 from the adsorber13 b is cooled by the cooling water passing through the cooling waterpipe 12 a, and is condensed into a liquid around the cooling water pipe12 a. This liquid moves to the evaporator 11 through the pipe 18 and isstored in the tray 11 b.

After the adsorbent 15 in the adsorber 13 a adsorbs a certain amount ofmoisture, adsorption efficiency of the adsorbent 15 is lowered.Therefore, after the elapse of a certain period of time, the controllerswitches the hot water supply destination from the adsorber 13 b to theadsorber 13 a, and also closes the valves 16 a and 17 b and opens thevalves 16 b and 17 a. Thus, moisture adsorption by the adsorbent 15 isstarted in the adsorber 13 b, and the adsorbent 15 in the adsorber 13 ais restored by moisture evaporation from the adsorbent 15.

The adsorption heat pump 10 operates continuously by switching the hotwater supply destination between the adsorbers 13 a and 13 b atintervals of a certain period of time as described above.

Meanwhile, as described above, the cooling water is supplied to thecooling water pipe 12 a in the condenser 12. Normally, circulating wateris used as the cooling water to be supplied to the condenser 12, and acooling device cools the circulating water so as not to increase thetemperature thereof. When the cooling device consumes a large amount ofpower, an energy-saving effect achieved by the use of the adsorptionheat pump is reduced. For this reason, a sprinkler cooling tower withrelatively low power consumption is often used as the cooling device.

However, the sprinkler cooling tower occupies a relatively large spacefor installation, making it difficult to use the adsorption heat pumpdescribed above in a relatively small-scale facility.

In the following embodiments, description will be given of an adsorptionheat pump system and a method of driving an adsorption heat pump, whichmay be used even in a relatively small-scale facility.

(1. First Embodiment) FIG. 2 is a schematic view illustrating anadsorption heat pump system according to a first embodiment.

An adsorption heat pump 20 includes an evaporator 21, a condenser 22disposed above the evaporator 21, adsorbers 23 a and 23 b disposed inparallel between the evaporator 21 and the condenser 22, and acontroller 30. A space inside the adsorption heat pump 20 isdepressurized to about 1/100 atm to 1/10 atm, for example.

Note that while two adsorbers 23 a and 23 b are disposed in parallelbetween the evaporator 21 and the condenser 22 in this embodiment, threeor more adsorbers may be disposed between the evaporator 21 and thecondenser 22.

The adsorption heat pump system according to this embodiment includesthe adsorption heat pump 20 described above, an air-cooling device 29and a cooling water circulating pump 31. The adsorption heat pump 20 isdisposed near an electronic device or the like which discharges wasteheat, for example. The air-cooling device 29 and the cooling watercirculating pump 31 are disposed outdoors.

A cooling water pipe 21 a through which cooling water passes and a tray21 b to store a refrigerant are provided in the evaporator 21. Whilewater, alcohol or the like is used as the refrigerant, water is used asthe refrigerant in this embodiment.

In each of the adsorbers 23 a and 23 b, a heat-transfer pipe 24 and anadsorbent (desiccant) 25 are provided. A valve 26 a is disposed betweenthe adsorber 23 a and the evaporator 21, and a valve 26 b is disposedbetween the adsorber 23 b and the evaporator 21. As the adsorbent 25,activated carbon, silica gel, zeolite or the like is used, for example.

A pressure sensor 41 a to detect a pressure inside the adsorber 23 a isdisposed in the adsorber 23 a, and a pressure sensor 41 b to detect apressure inside the adsorber 23 b is disposed in the adsorber 23 b.Signals to be outputted from these pressure sensors 41 a and 41 b aretransmitted to the controller 30.

In the condenser 22, a cooling water pipe 22 a with a number of platefins attached thereto is disposed. A valve 27 a is disposed between thecondenser 22 and the adsorber 23 a, and a valve 27 b is disposed betweenthe condenser 22 and the adsorber 23 b. The condenser 22 and theevaporator 21 are connected by a pipe 28.

A pressure sensor 22 b to detect a pressure inside the condenser 22 isdisposed in the condenser 22. A signal to be outputted from thispressure sensor 22 b is also transmitted to the controller 30.

As the valves 26 a, 26 b, 27 a and 27 b, magnetic valves controlled tobe opened and closed by the controller 30 may be used. However,differential pressure-driven valves are used in this embodiment, whichare automatically opened and closed by a pressure difference, therebyachieving further power saving.

The air-cooling device 29 includes a pipe 29 b with a number of platefins 29 a attached thereto and a blast fan 29 c. The air-cooling device29 cools cooling water (refrigerant) passing through the pipe 29 b byblowing the outside air between the plate fins 29 a from the blast fan29 c. An inlet of the air-cooling device 29 is connected to an outlet ofthe cooling water pipe 22 a in the condenser 22 through a pipe 35 a, andan outlet of the air-cooling device 29 is connected to the suction sideof the cooling water circulating pump 31 through a pipe 35 b. Also, theejection side of the cooling water circulating pump 31 is connected toan inlet of the cooling water pipe 22 a in the condenser 22 through apipe 35 c.

A temperature sensor 42 a to detect a temperature of cooling water to besupplied to the cooling water pipe 22 a in the condenser 22 and a flowrate sensor 43 to detect a flow rate of the cooling water are disposedin the pipe 35 c. Also, a temperature sensor 42 b to detect atemperature of the cooling water to be discharged from the condenser 22is disposed in the pipe 35 a. Signals to be outputted from thesetemperature sensors 42 a and 42 b and the flow rate sensor 43 are alsotransmitted to the controller 30.

The controller 30 adjusts the flow rate of the cooling water to besupplied to the condenser 22 by controlling the cooling watercirculating pump 31 based on the signals outputted from the pressuresensors 22 b, 41 a and 41 b, the temperature sensors 42 a and 42 b andthe flow rate sensor 43. Also, the controller 30 supplies hot wateralternately to the heat-transfer pipe 24 in the adsorber 23 a and theheat-transfer pipe 24 in the adsorber 23 b repeatedly each for thecertain period of time, the hot water being heated by heat dischargedfrom the electronic device or the like.

A method of driving an adsorption heat pump in the above adsorption heatpump system will be described below.

Here, it is assumed that, in an initial state, the adsorbent 25 in theadsorber 23 a is in a dried state, while the adsorbent 25 in theadsorber 23 b is in a moisture-adsorbing state. It is also assumed thathot water heated to 60° C. to 90° C. by the heat discharged from theelectronic device is supplied to the heat-transfer pipe 24 in theadsorber 23 b.

(Restoration Process) Since the hot water is supplied to theheat-transfer pipe 24 in the adsorber 23 b, moisture evaporates from theadsorbent 25 in the adsorber 23 b and the pressure inside the adsorber23 b is increased. Accordingly, the valve 26 b is closed and the valve27 b is opened, causing water vapor to enter into the condenser 22 fromthe adsorber 23 b. Meanwhile, the pressure inside the condenser 22 isincreased to be higher than that inside the adsorber 23 a, and the valve27 a is closed.

The water vapor that has entered into the condenser 22 from the adsorber23 b is cooled by the cooling water passing through the cooling waterpipe 22 a, and is condensed into a liquid. This liquid moves to theevaporator 21 through the pipe 28 and is stored in the tray 21 b.

By continuously supplying the hot water to the heat-transfer pipe 24 inthe adsorber 23 b for the certain period of time, the adsorbent 25 inthe adsorber 23 b is restored (dried).

(Adsorption Process) In the adsorber 23 a, moisture adsorption by theadsorbent 25 causes the pressure inside the adsorber 23 a to be lowerthan that inside the evaporator 21, and the valve 26 a is opened.Accordingly, the pressure inside the evaporator 21 is also reduced andthe water as the refrigerant evaporates, depriving the cooling waterpipe 21 a of latent heat. As a result, the temperature of the waterpassing through the cooling water pipe 21 a is lowered, and thelow-temperature cooling water is discharged from the cooling water pipe21 a. This cooling water is used for room air conditioning, cooling ofelectronic devices, and the like, for example.

A water vapor generated inside the evaporator 21 enters into theadsorber 23 a through the valve 26 a, and is adsorbed by the adsorbent25.

Note that heat is generated when the adsorbent 25 adsorbs the moisture.Therefore, it is preferable to cool the adsorbent 25 by passing thecooling water through the heat-transfer pipe 24 in the adsorber (theadsorber 23 a or the adsorber 23 b) carrying out the adsorption process.In such a case, some of the cooling water to be discharged from theair-cooling device 29, for example, may be passed through theheat-transfer pipe 24 in the adsorber carrying out the adsorptionprocess, or another air-cooling device may be separately provided forthe adsorber.

(Switch between Restoration Process and Adsorption Process) After theadsorbent 25 in the adsorber 23 a adsorbs a certain amount of moisture,adsorption efficiency of the adsorbent 25 is lowered. Therefore, afterthe elapse of a certain period of time, the controller 30 switches thehot water supply destination from the adsorber 23 b to the adsorber 23a. Then, in the adsorber 23 a, the moisture adsorbed by the adsorbent 25evaporates, and thus the pressure inside the adsorber 23 a is increasedto close the valve 26 a and open the valve 27 a. Thus, a vapor generatedin the adsorber 23 a enters into the condenser 22.

Meanwhile, in the adsorber 23 b, the stop of hot water supply reducesthe pressure inside the adsorber 23 b. Thus, the valve 27 b is closedand the valve 26 b is opened, causing the vapor generated in theevaporator 21 to enter into the adsorber 23 b.

The adsorption heat pump 20 operates continuously by switching the hotwater supply destination between the adsorbers 23 a and 23 b at theintervals of the certain period of time as described above.

(Control of Cooling Water Supplied to Condenser) In the condenser 22,moisture condensation generates condensation heat, which increases thetemperature of the cooling water passing through the cooling water pipe22 a. In this embodiment, the cooling water is cooled by the air-coolingdevice 29 and resupplied to the condenser 22. In this case, when thereis a small difference between the outside air temperature and thetemperature of the cooling water discharged from the condenser 22,heat-exchange efficiency of the air-cooling device 29 is reduced,leading to wasteful power consumption. For this reason, in thisembodiment, the flow rate of the cooling water to be supplied to thecondenser 22 is adjusted by controlling the cooling water circulatingpump 31 such that the temperature of the cooling water discharged fromthe condenser 22 is higher than the outside air temperature by 2° C. ormore, preferably 5° C. or more.

However, when the flow rate of the cooling water to be supplied to thecondenser 22 is reduced so as to increase the heat-exchange efficiencyof the air-cooling device 29, the amount of moisture to be condensedinside the condenser 22 is reduced and dew condensation occurs on aninner wall surface of the adsorber (the adsorber 23 a or the adsorber 23b) carrying out the restoration process. The moisture condensed into dewdrops on the inner wall surface of the adsorber evaporates from theinner wall surface and is adsorbed by the adsorbent 25 in the nextadsorption process. Therefore, although the dew condensation on theinner wall surface of the adsorber does not cause the adsorption heatpump 20 to stop its operation, the moisture evaporation inside theadsorber does not contribute to cooling of the cooling water passingthrough the cooling water pipe 21 a in the evaporator 21, leading toperformance degradation of the adsorption heat pump 20.

Therefore, in this embodiment, the pressure inside the condenser 22 andthe pressure inside the adsorber (the adsorber 23 a or the adsorber 23b) carrying out the restoration process are measured by the pressuresensors 22 b, 41 a and 41 b disposed in the condenser 22 and theadsorbers 23 a and 23 b. When a difference between the pressure insidethe condenser 22 and the pressure inside the adsorber carrying out therestoration process is outside a predetermined range, the controller 30controls an ejection amount of the cooling water circulating pump 31such that the difference between the pressure inside the condenser 22and the pressure inside the adsorber carrying out the restorationprocess is within the predetermined range.

A small difference between the pressure inside the condenser 22 and thepressure inside the adsorber carrying out the restoration process meansa small amount of moisture to be condensed in the condenser 22 and ahigh likelihood of occurrence of dew condensation in the adsorber. It ispreferable that there is a large difference between the pressure insidethe condenser 22 and the pressure inside the adsorber carrying out therestoration process. However, the difference between the pressure insidethe condenser 22 and the pressure inside the adsorber carrying out therestoration process is limited by the outside air temperature and is notincreased more than a certain level.

In this embodiment, the amount of cooling water to be supplied to thecondenser 22 is adjusted by controlling the cooling water circulatingpump 31 such that the difference in pressure between the condenser 22and the adsorber (the adsorber 23 a or the adsorber 23 b) carrying outthe restoration process falls within the range of 1 kPa to 2 kPa.

However, an appropriate range of the difference in pressure between thecondenser 22 and the adsorber (the adsorber 23 a or the adsorber 23 b)carrying out the restoration process varies depending on the temperatureof the hot water to be supplied to the adsorption heat pump 20, the kindof the adsorbent 25, and the like. It is preferable that an appropriatepressure range which meets conditions is obtained beforehand by anexperiment or the like and recorded in the controller 30.

(Effects) In the adsorption heat pump system according to thisembodiment, as described above, the cooling water discharged from thecondenser 22 is cooled by the air-cooling device 29 including the pipe29 b with the fins 29 a attached thereto and the blast fan 29 c. Thus,no large-size equipment such as a sprinkler cooling tower is used, andthe adsorption heat pump may be used even in a small-scale facility.

Moreover, in the adsorption heat pump system according to thisembodiment, the flow rate of cooling water to be supplied to thecondenser 22 is adjusted such that the difference between the pressureinside the condenser 22 and the pressure inside the adsorber 23 a or 23b falls within the predetermined range. Thus, the heat-exchangeefficiency of the air-cooling device may be increased to enable furtherpower saving. Moreover, dew condensation of moisture (refrigerant) maybe prevented in the adsorber 23 a or 23 b carrying out the restorationprocess. Thus, the performance degradation of the adsorption heat pump20 is avoided.

MODIFIED EXAMPLE 1

In the first embodiment described above, the cooling water is cooled byblowing the outside air onto the fins 29 a from the blast fan 29 c inthe air-cooling device 29. However, a spray pipe 51 a may be provided asillustrated in FIG. 3A, for example, to spray water onto the fins 29 a.In this case, the water deprives the fins 29 a of latent heat duringvaporization. Thus, cooling capacity of the air-cooling device 29 isincreased compared with the case where the outside air is simply blownonto the fins 29 a.

Alternatively, as illustrated in FIG. 3B, water may be sprayed from aspray pipe 51 b disposed between the blast fan and the fins 29 a, andair of which temperature is lowered by vaporization heat may be sprayedonto the fins 29 a. Also in this case, the cooling capacity of theair-cooling device 29 is increased compared with the case where theoutside air is simply blown onto the fins 29 a, as in the case of FIG.3A.

MODIFIED EXAMPLE 2

In the first embodiment described above, whether or not there is dewcondensation in the adsorber is determined based on the differencebetween the pressure inside the condenser 22 and the pressure inside theadsorber (the adsorber 23 a or the adsorber 23 b) carrying out therestoration process. However, as illustrated in FIG. 4, for example,humidity sensors 52 a and 52 b may be disposed inside the adsorbers 23 aand 23 b, and the controller 30 may determine whether or not there isdew condensation based on outputs from the humidity sensors 52 a and 52b.

Alternatively, as illustrated in FIG. 5, for example, dew condensationsensors 53 a and 53 b whose electrical conductivity is changed by dewcondensation may be disposed inside the adsorbers 23 a and 23 b, and thecontroller 30 may determine whether or not there is dew condensationbased on outputs from the dew condensation sensors 53 a and 53 b.

MODIFIED EXAMPLE 3

When the amount of condensation heat generated during condensation ofwater vapor in the condenser 22 is smaller than the amount of heatabsorbed from the hot water by the adsorber (the adsorber 23 a or theadsorber 23 b) carrying out the restoration process, dew condensationoccurs in the adsorber due to insufficient condensation capacity.

In Modified Example 3, temperature sensors 54 a and 54 b to detect thetemperature of hot water supplied to the adsorbers 23 a and 23 b andtemperature sensors 55 a and 55 b to detect the temperature of hot waterdischarged from the adsorbers 23 a and 23 b are provided as illustratedin FIG. 6. Also, flow rate sensors 56 a and 56 b are provided to detectflow rates of hot water passing through the heat-transfer pipes 24 inthe adsorbers 23 a and 23 b.

The controller 30 calculates an amount of heat absorbed by the adsorber(the adsorber 23 a or the adsorber 23 b) carrying out the restorationprocess from the outputs from the temperature sensors 54 a, 54 b, 55 aand 55 b and the flow rate sensors 56 a and 56 b. The controller 30 alsocalculates an amount of condensation heat in the condenser 22 from theoutputs from the temperature sensors 42 a and 42 b and the flow ratesensor 43. Then, the controller 30 adjusts the cooling water circulatingpump 31 such that the amount of heat absorbed by the adsorber and theamount of condensation heat in the condenser 22 become the same. Thus,the same effects as those achieved by the above embodiment may beachieved.

EXPERIMENTAL EXAMPLE

Hereinafter, description will be given of results obtained by actuallymanufacturing the adsorption heat pump system according to the firstembodiment and checking the performance thereof.

As an experimental example, an adsorption heat pump system illustratedin FIG. 7 is manufactured. In FIG. 7, the same components as those inFIGS. 2 and 4 to 6 are denoted by the same reference numerals, anddetailed description thereof is omitted.

In each of adsorbers 23 a and 23 b, five copper corrugated fin heatexchangers are disposed, each filled with 200 g of activated carbonsubjected to hydrophilic treatment. Also, dew condensation sensors 53 aand 53 b are disposed inside the adsorbers 23 a and 23 b.

In an evaporator 21 and a condenser 22, copper plate fin heat exchangershaving the same shape as those disposed in the adsorbers 23 a and 23 bare disposed. Note, however, that the heat exchangers in the evaporator21 and the condenser 22 are filled with no activated carbon.

As valves 26 a and 26 b between the evaporator 21 and the adsorbers 23 aand 23 b and valves 27 a and 27 b between the condenser 22 and theadsorbers 23 a and 23 b, differential pressure-driven valves made of PET(polyethylene terephthalate) are used.

A temperature sensor 42 a to detect the temperature of cooling water tobe supplied to the condenser 22 and a flow rate sensor 43 to detect theflow rate of the cooling water are disposed in a pipe 35 c on the inletside of the condenser 22. Also, a temperature sensor 42 b to detect thetemperature of the cooling water to be discharged from the condenser 22is disposed in a pipe 35 a on the outlet side of the condenser 22.Signals to be outputted from these temperature sensors 42 a and 42 b andthe flow rate sensor 43 are inputted to a controller 30.

Moreover, temperature sensors 54 a and 54 b and flow rate sensors 56 aand 56 b are disposed on the inlet side of heat-transfer pipes 24 in theadsorbers 23 a and 23 b, and temperature sensors 55 a and 55 b aredisposed on the outlet side thereof. Signals to be outputted from thesetemperature sensors 54 a, 54 b, 55 a and 55 b and the flow rate sensors56 a and 56 b are also inputted to the controller 30. Furthermore, atemperature sensor 57 is provided to detect the outside air temperature,and a signal to be outputted from the temperature sensor 57 is alsoinputted to the controller 30.

In the adsorption heat pump system thus configured, cooling water at 18°C. is supplied to a cooling water pipe 21 a in the evaporator 21. Also,hot water at 60° C. is supplied to the adsorber 23 b which carries outthe restoration process, and cooling water cooled to 26° C. by theair-cooling device 29 is supplied to the condenser 22 and the adsorber23 a which carries out the adsorption process. Then, the flow rate ofthe cooling water supplied to the condenser 22 is controlled such that apressure difference between the condenser 22 and the adsorber 23 b iswithin the range of 1 kPa to 2 kPa. Note that the outside airtemperature in this event is 25° C.

First, when the hot water at 60° C. is passed at a flow rate of 5 L(liter)/min through the adsorber 23 b, 400 W of heat on average isabsorbed by the adsorber 23 b, and a maximum heat absorption rate is 600W. In this event, the temperature of the cooling water discharged fromthe cooling water pipe 21 a in the evaporator 21 is 15° C.

Next, the flow rate of the cooling water supplied to the condenser 22 isset to 4 L/min. In this case, the temperature of the cooling waterdischarged from the condenser 22 is 27.4° C. When the flow rate of thecooling water supplied to the condenser 22 is set to 1 L/min to 2 L/min,the temperature of the cooling water discharged from the condenser 22becomes 28.8° C. to 31.6° C.

Then, when the flow rate of the cooling water is set to 1 L/min or less,the temperature of the cooling water discharged from the condenser 22becomes 34° C. In this event, occurrence of dew condensation inside theadsorber 23 b is confirmed by the dew condensation sensor 53 b.Therefore, the flow rate of the cooling water supplied to the condenser22 is set back to 2 L/min.

As described above, the flow rate of the cooling water supplied to thecondenser 22 is appropriately adjusted based on the presence or absenceof dew condensation and a difference in cooling water temperaturebetween the inlet side and outlet side of the condenser 22. As a result,it is confirmed that the cooling water discharged from the condenser 22may be cooled using the outside air while avoiding the dew condensationin the adsorber 23 b. Note that when the cooling capacity of theair-cooling device 29 may be insufficient, the cooling capacity of theair-cooling device 29 may be improved by spraying a small amount ofwater onto the fins 29 a as described above.

(2. Second Embodiment) FIG. 8 is a schematic view illustrating anadsorption heat pump system according to a second embodiment.

The adsorption heat pump system illustrated in FIG. 8 includes twoadsorption heat pumps 60 a and 60 b, a controller 70, air-coolingdevices 81 and 84, a hot water supply source 82, a cooling water tank 83and switching units 71 and 72. Note that although pumps are actuallyconnected to the air-cooling devices 81 and 84, the hot water supplysource 82 and the cooling water tank 83, respectively, FIG. 8 omits theillustration of those pumps.

Each of the adsorption heat pumps 60 a and 60 b includes an evaporatorand condenser 61 and an adsorber 62. The insides of the adsorption heatpumps 60 a and 60 b are depressurized to about 1/100 atm to 1/10 atm,for example.

The evaporator and condenser 61 includes a heat-transfer pipe 63 throughwhich cooling water passes and a tray 64 to store a refrigerant. Theheat-transfer pipe 63 has plate fins 63 a provided thereto. Atemperature sensor 75 a and a flow rate sensor 76 are disposed on theinlet side of the heat-transfer pipe 63, and a temperature sensor 75 bis disposed on the outlet side thereof.

The adsorber 62 includes a heat-transfer pipe 65 and an adsorbent 66. Atemperature sensor 73 a and a flow rate sensor 74 are disposed on theinlet side of the heat-transfer pipe 65, and a temperature sensor 73 bis disposed on the outlet side thereof.

Note that although the adsorber 62 is disposed above the evaporator andcondenser 61 in FIG. 8, the adsorber 62 may be disposed lateral to theevaporator and condenser 61. Also in this embodiment, water is used asthe refrigerant enclosed in the adsorption heat pumps 60 a and 60 b.

Each of the air-cooling devices 81 and 84 includes a pipe with platefins attached thereto and a blast fan for blowing the outside air towardthe plate fins. The hot water supply source 82 supplies hot water heatedby heat discharged from an electronic device or the like.

The cooling water tank 83 stores cooling water cooled by the adsorptionheat pumps 60 a and 60 b. The cooling water stored in the cooling watertank 83 is used for room air conditioning, cooling of electronicdevices, and the like.

The controller 70 controls the switching unit 72 to allow the adsorptionheat pumps 60 a and 60 b to alternately carry out the adsorption processand the restoration process.

Hereinafter, description will be given of a method of driving theadsorption heat pumps in the adsorption heat pump system according tothis embodiment. Here, it is assumed that, in an initial state, theadsorbent 66 in the adsorber 62 in the adsorption heat pump 60 a is in amoisture-adsorbing state, while the adsorbent 66 in the adsorber 62 inthe adsorption heat pump 60 b is in a dried state.

In this case, the controller 70 controls the switching unit 71 toconnect the adsorber 62 in the adsorption heat pump 60 a with the hotwater supply source 82 and to connect the adsorber 62 in the adsorptionheat pump 60 b with the air-cooling device 81. At the same time, thecontroller 70 controls the switching unit 72 to connect the evaporatorand condenser 61 in the adsorption heat pump 60 a with the air-coolingdevice 84 and to connect the evaporator and condenser 61 in theadsorption heat pump 60 b with the cooling water tank 83.

Then, the hot water is supplied to the adsorber 62 in the adsorptionheat pump 60 a and a water vapor is generated by evaporation of moistureadsorbed on the adsorbent 66. This water vapor is cooled into a liquidby the evaporator and condenser 61 and then stored in the tray 64.

Meanwhile, in the adsorption heat pump 60 b, moisture is adsorbed ontothe adsorbent 66 in the adsorber 62 and thus the pressure inside theadsorption heat pump 60 b is reduced. Accordingly, the water stored inthe tray 64 evaporates to deprive the heat-transfer pipe 63 of latentheat. As a result, the temperature of the cooling water passing throughthe heat-transfer pipe 63 is lowered.

After the elapse of a certain period of time, the controller 70 controlsthe switching unit 71 to connect the adsorber 62 in the adsorption heatpump 60 a with the air-cooling device 81 and to connect the adsorber 62in the adsorption heat pump 60 b with the hot water supply source 82. Atthe same time, the controller 70 controls the switching unit 72 toconnect the evaporator and condenser 61 in the adsorption heat pump 60 awith the cooling water tank 83 and to connect the evaporator andcondenser 61 in the adsorption heat pump 60 b with the air-coolingdevice 84.

Then, in the adsorption heat pump 60 a, moisture is adsorbed onto theadsorbent 66 in the adsorber 62 and thus the pressure inside theadsorption heat pump 60 a is reduced. Accordingly, the water stored inthe tray 64 evaporates to deprive the heat-transfer pipe 63 of latentheat. As a result, the temperature of the cooling water passing throughthe heat-transfer pipe 63 is lowered.

Meanwhile, the hot water is supplied to the adsorber 62 in theadsorption heat pump 60 b and a water vapor is generated by evaporationof moisture adsorbed on the adsorbent 66. This water vapor is cooled andcondensed into a liquid by the evaporator and condenser 61 and thenstored in the tray 64.

The low-temperature cooling water is continuously supplied to thecooling water tank 83 by the controller 70 controlling the switchingunits 71 and 72 at intervals of a certain period of time as describedabove.

The controller 70 acquires the temperatures of the cooling water or hotwater on the inlet and outlet sides of the heat-transfer pipes 65 and 63in the adsorption heat pumps 60 a and 60 b from the temperature sensors73 a, 73 b, 75 a and 75 b, and the flow rates of the cooling water orhot water from the flow rate sensors 74 and 76. Then, the controller 70adjusts the amount of cooling water to be supplied to the evaporator andcondenser 61 from the air-cooling device such that the amount of heatadsorbed by the adsorber 62 carrying out the adsorption process becomesequal to the amount of condensation heat in the evaporator and condenser61 carrying out the restoration process.

As in the case of the first embodiment, the adsorption heat pump systemaccording to this embodiment also uses no large-size equipment such as asprinkler cooling tower and thus may be used even in a small-scalefacility.

All examples and conditional language recited herein are intended forthe pedagogical purposes of aiding the reader in understanding theinvention and the concepts contributed by the inventor to further theart, and are not to be construed as limitations to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the invention. Although one or more embodiments of thepresent invention have been described in detail, it should be understoodthat the various changes, substitutions, and alterations could be madehereto without departing from the spirit and scope of the invention.

What is claimed is:
 1. An adsorption heat pump system comprising: anadsorption heat pump including a condenser configured to condense avapor of a refrigerant; an air-cooling device configured to air-cool acoolant discharged from the condenser in the adsorption heat pump and toresupply the air-cooled coolant to the condenser; and a controllerconfigured to control a flow rate of the coolant to be supplied to thecondenser according to a difference in temperature between the coolantsupplied to the condenser and the coolant discharged from the condenser.2. The adsorption heat pump system according to claim 1, wherein theadsorption heat pump further includes an evaporator configured togenerate a vapor of the refrigerant and a plurality of adsorbersdisposed in parallel between the evaporator and the condenser, and eachof the plurality of adsorbers includes an adsorbent configured to adsorbthe vapor of the refrigerant and a heat-transfer pipe through which hotwater passes at intervals of a certain period of time.
 3. The adsorptionheat pump system according to claim 2, wherein the controller controlsthe flow rate of the coolant to be supplied to the condenser such thatthe difference in temperature between the coolant supplied to thecondenser and the coolant discharged from the condenser is equal to orhigher than a preset temperature and no dew condensation occurs withinthe adsorber through which the hot water is passing.
 4. The adsorptionheat pump system according to claim 3, further comprising: a sensorconfigured to detect whether or not there is dew condensation withineach of the plurality of adsorbers, wherein a signal outputted from thesensor is inputted to the controller.
 5. The adsorption heat pump systemaccording to claim 3, wherein the controller controls the flow rate ofthe coolant to be supplied to the condenser such that an amount of heatadsorbed by the adsorber through which the hot water is passing becomesequal to an amount of condensation heat in the condenser.
 6. Theadsorption heat pump system according to claim 2, wherein differentialpressure-driven valves configured to be automatically opened and closedby a pressure difference are disposed between the evaporator and theplurality of adsorbers and between the condenser and the plurality ofadsorbers.
 7. The adsorption heat pump system according to claim 1,wherein the air-cooling device includes a pipe through which the coolantpasses, cooling fins attached to the pipe, a blast fan configured toblow outside air onto the cooling fins, and a spray pipe configured tospray water onto the cooling fins.
 8. The adsorption heat pump systemaccording to claim 1, wherein the air-cooling device includes a pipethrough which the coolant passes, cooling fins attached to the pipe, ablast fan configured to blow outside air onto the cooling fins, and aspray pipe configured to spray water between the cooling fins and theblast fan.
 9. The adsorption heat pump system according to claim 2,wherein the controller passes the hot water through the plurality ofadsorbers in turn at the intervals of the certain period of time. 10.The adsorption heat pump system according to claim 1, wherein theadsorbent contains at least one of activated carbon, silica gel andzeolite.
 11. A method of driving an adsorption heat pump configured tocool a coolant discharged from a condenser in the adsorption heat pumpby using an air-cooling device, comprising: controlling a flow rate ofthe coolant to be supplied to the condenser such that a difference intemperature between the coolant supplied to the condenser and thecoolant discharged from the condenser is equal to or more than a setvalue.
 12. The method of driving an adsorption heat pump, according toclaim 11, wherein the air-cooling device is disposed outdoors.
 13. Themethod of driving an adsorption heat pump, according to claim 11,wherein the hot water is water heated by heat discharged from anelectronic device.
 14. The method of driving an adsorption heat pump,according to claim 11, wherein the adsorption heat pump further includesan evaporator configured to generate a vapor of a refrigerant and aplurality of adsorbers disposed in parallel between the evaporator andthe condenser, and each of the plurality of adsorbers includes anadsorbent configured to adsorb the vapor of the refrigerant and aheat-transfer pipe through which hot water passes at intervals of acertain period of time.
 15. The method of driving an adsorption heatpump, according to claim 14, comprising: controlling the flow rate ofthe coolant to be supplied to the adsorption heat pump such that thedifference in temperature between the coolant supplied to the condenserand the coolant discharged from the condenser is equal to or higher thana preset temperature and no dew condensation occurs within the adsorberthrough which the hot water is passing.
 16. The method of driving anadsorption heat pump, according to claim 15, further comprising:controlling the flow rate of the coolant to be supplied to the condensersuch that an amount of heat adsorbed by the adsorber having the hotwater supplied thereto becomes equal to an amount of condensation heatin the condenser.
 17. The method of driving an adsorption heat pump,according to claim 14, wherein differential pressure-driven valvesconfigured to be automatically opened and closed by a pressuredifference are disposed between the evaporator and the plurality ofadsorbers and between the condenser and the plurality of adsorbers.